The truck is a 93 F150. The problem is that the fan only works on hi. The other 3 speeds do not work. There are 4 wires entering the switch. 3 have power coming in, the 4th(black) is ground I assume. The contacts on the switch appear to be fine. Is there any thing else that could be wrong.

 

Auto/truck fan motors use a multi-resistor pack to drop the voltage at settings other than HI. Sounds to me like you need a new one. Not sure where it is on your truck, but usually they are mounted in the heater inlet plenum so that the air flow keeps them from overheating. Look for a 4 wire connector plugged into the heater plenum. If it's going to a removable plate, you found it. Pull the plate and flip it over. The 3 resistors are visible on the back side. They look like little coils of wire, cause that's what they are.

Unplug the connector and take the whole plate off. You can't fix it, but you should be able to pick up a new resistor pack at most any parts store, just be sure to have the old one in your hand to make certain they sell you the right one.

 

Thanks alot
I will replace it.